Always include lymphomatous meningitis in the differential diagnosis; see CNS lymphoma
Numerous conditions can present with similar symptomatology as carcinomatous meningitis and should be taken into consideration whenever patients present with indistinguishable signs and symptoms.
Intraparenchymal primary brain lesions or metastasis can present with similar symptoms. Calvarial and dura matter involvement should be ruled out. Leptomeningeal metastasis can present separately or co-exist with the involvement of these regions.
Chronic or recurrent meningitis caused by a variety of bacterial, fungal, viral, or protozoal organisms can also resemble CM. Autoimmune and drug-induced causes of meningitis should also be considered.
Paraneoplastic syndromes, including Lambert-Eaton syndrome, Myasthenic crisis, cerebellar degeneration, encephalomyelitis, neuropathy, and limbic encephalitis, can mimic carcinomatous meningitis and are associated with advanced-stage disease.